Real numbers from Rose Cottage using Octopus Intelligent Octopus Go. The payback problem. Which EVs can do it. And when V2H actually makes sense.
Your new electric car isn't just a vehicle—it's a mobile battery with 60–80 kWh of storage. Plug it into a V2H (Vehicle-to-Home) charger, and it can pump that power back into your house during evening peaks, grid emergencies, or when you want backup. No solar panels needed. No expensive home battery required.
But here's the catch: a V2H charger costs £5,500–6,500 installed. The energy savings are... complicated. At our test house—Rose Cottage, Oxfordshire, running Octopus Intelligent Octopus Go—adding a V2H charger costs you money, not saves it.
This article walks through the real numbers, explains which EVs can actually do it, and shows you the decision tree: when V2H makes sense for your home, and when a cheap smart charger + the right tariff wins.
Your EV charger is bidirectional. Power flows in (charging your car) or out (discharging to your house). Simple. Residential only.
Your charger is also bidirectional and talks to the grid operator. The car becomes part of the UK's virtual power station. Grid sends signals; your charger responds. More complex, requires firmware updates, and Ofgem approval. V2G is coming (Octopus plans 2027), but today it's niche.
Your car's emergency outlet powers a kettle or laptop for a few hours via a portable 3 kW AC plug. Limited, consumer-friendly, already in Tesla Cybertruck and Hyundai Ioniq 5, but not home-scale.
This article focuses on V2H: discharge during expensive peak hours (4–10 pm), recharge at night when it's cheap (23:30–05:30 on IOG tariffs).
Most V2H advocates pitch it as a grid-resilience story: When the power cuts out, your EV powers the house for days. That's real. A 77 kWh ID.7 carries ~62 kWh usable—enough to run a 4-bed home for 4–5 days if you're efficient.
But the financial story is weaker. Here are the gotchas:
Every cycle—charge, store, discharge—loses ~15% to inverter, cable, and battery resistance. You buy cheap at 6.90p/kWh at night, sell expensive at 30.37p/kWh in the evening, but lose 15% to physics. The math barely works.
V2H only pays if you have a tariff with a big day/night spread. Octopus IOG delivers: 6.90p at night, 30.37p during the day. Most standard tariffs (blended ~24–30p) don't give you enough margin to overcome roundtrip loss. Switch tariff, and your business case evaporates.
At Rose Cottage, the annual energy benefit of V2H—the £258 you earn by shifting 1,290 kWh from peak hours—is completely wiped out by the £550 annual cost of amortising a £5,500 charger over 10 years. You don't break even on energy alone.
The good news: Most mainstream EVs launched since 2022 support bidirectional charging via DC.
The bad news: It's fragmented by charger type (CCS2 vs CHAdeMO) and by region (UK firmware rollout is inconsistent).
| Vehicle | Charger Type | Status | Notes |
|---|---|---|---|
| VW ID.3 / ID.4 / ID.7 | CCS2 | ✓ Live | OTA update Dec 2023; 62–82 kWh models; Wallbox Quasar/Zaptec Pro tested |
| VW ID.Buzz | CCS2 | ✓ Live | Recently launched; same platform as ID.7 |
| Kia EV9 | CCS2 | ✓ Live | Full V2G support; 99 kWh battery |
| Kia Niro | CCS2 | ✓ V2H | V2G pending (UK charger firmware) |
| Skoda Enyaq 85 | CCS2 | ✓ Live | Shares MEB platform with VW |
| Cupra Tavascan VZ | CCS2 | ✓ Live | Shares MEB platform |
| Audi Q4 e-tron | CCS2 | ✓ Live | Shares MEB platform |
| Polestar 3 | CCS2 | ✓ Live | Volvo-owned; Linqing platform |
| Volvo EX90 | CCS2 | ✓ Live | Linqing platform |
| Renault 5 E-Tech | CCS2 | ✓ Live (France) | UK 2026; CMF platform |
| Nissan Leaf (new, 2024+) | CHAdeMO | ⚠ Coming | G99 approved; UK service launch 2026 |
| Nissan e-NV200 | CHAdeMO | ✓ With Indra | Indra V2G charger required (~£4,500) |
| NOT Supported | Why |
|---|---|
| Tesla Model 3 / Y | No bidirectional hardware; Tesla Powershare is Cybertruck only (2027+) |
| Hyundai Ioniq 5 | V2L only in UK (vehicle + charger firmware limitation) |
| BMW i4 | Vehicle support; charger ecosystem fragmented |
| Jaguar I-PACE | Aging platform; ZF charger ecosystem winding down |
Key: Just because an EV supports V2H doesn't mean the charger ecosystem is mature. VW ID-series is the safest bet in the UK; new Nissan Leaf is coming; Tesla and Hyundai are laggards.
Here's where V2H hits a wall: chargers are expensive and immature.
DC, 11 kW, CCS2, wall-mounted
Cost: £5,500–6,500 fitted (UK supply chain unclear; US launch confirmed; UK status TBC)
Pros: Compact, modern software, integration with Octopus planned
Cons: Limited field data; Wallbox customer support still growing
AC/DC hybrid, 11 kW, CCS2
Cost: £5,500–6,000 fitted
Pros: Used in Octopus Power Pack; EU-tested; live in UK via installer networks
Cons: Larger footprint; less integrated UK documentation
AC bidirectional, 7.4 kW, CCS2
Cost: £4,500–5,200 fitted
Pros: Smaller, lighter, simpler; launched late 2025
Cons: AC charging slower than DC (not ideal for daily cycles)
DC, 7–11 kW, CHAdeMO only
Cost: £4,000–4,500 fitted
Pros: UK-made; proven; Nissan Leaf focus
Cons: CHAdeMO is aging (phase-out by 2030 EU target); locks you into Leaf/e-NV200 ecosystem
DC, 11.5 kW, dual-voltage (400V/800V), GaN microinverters
Cost: ~£5,000–5,500 (estimated; demo UK Feb 2026)
Availability: Volume production Q4 2026 (not yet on sale in UK)
Pros: Proven Enphase microinverter quality; 400V + 800V compatibility; EU G99-certified
Cons: Waiting game; integration with UK tariffs TBC
Wallbox Pulsar, Zappi, Hypervolt — 7.4 kW AC, one-way
Cost: £700–1,200 fitted (sometimes grant-subsidised)
Pros: Cheap, reliable, IOG-compatible, sufficient for most daily charging
Cons: No backup power; no arbitrage; limited to overnight charging
Extra cost over a standard smart charger
Let's walk through real numbers.
| Item | Cost | Notes |
|---|---|---|
| Lease | £7,056 | £588/month × 12 |
| Diesel fuel | £1,320 | 12,000 mi ÷ 50 mpg = 240 gal @ £5.50/gal |
| Road tax | Included | Fleet package |
| Maintenance | Included | Lease warranty |
| Total | £8,376/year |
Lease: VW ID.7 Tourer (250kW 4MOTION GTX, 86kWh), 12,000 miles/year
Price: £386.52/month (LeaseLoco, personal factory order, 2-yr term)
Charging: 4,300 kWh/year, ~88% at night on IOG
| Item | Cost | Notes |
|---|---|---|
| Lease | £4,638 | £386.52/month × 12 (includes warranty, road tax, roadside) |
| Charging: IOG night rate | £261 | 4,300 kWh/year @ 6.90p/kWh (88% night) |
| Insurance | £500 | Group 43E, equiv. to Mercedes |
| Maintenance | £0 | Included in lease |
| Total | £5,399/year |
36% reduction in annual motoring cost. The biggest win is the tariff, not the car.
The biggest win here is not the car; it's the tariff. Octopus IOG is 6.90p/kWh at night vs. 30–35p on most standard tariffs. That switch—from blended ~30p to 6.90p at night—cuts Rose Cottage's household electricity from £3,750/year to £752/year, before adding the EV. Adding the EV adds only £261.
Charger: Wallbox Quasar 2 (or Zaptec Pro), £5,500 fitted, 10-year amortisation = £550/year
V2H Arbitrage: Discharge at 30.37p peak, recharge at 6.90p night, minus 15% roundtrip loss
| Item | Cost | Notes |
|---|---|---|
| Lease + IOG charging | £5,399 | From Scenario A |
| Wallbox amortised | £550 | £5,500 ÷ 10 years |
| V2H arbitrage (net) | −£38 | Gross saving ~£258/year; 15% loss means net is a cost |
| Total | £5,911/year |
30% reduction — but costs £512/year more than Scenario A
Here's the uncomfortable truth:
Use this decision tree:
If your power cuts out for 12+ hours once a year (or you're in an area where it might), the backup value justifies £550/year. A 62 kWh usable battery = 4–5 days of heating + lights + fridge at modest consumption. That's insurance. If a multi-day outage costs you (spoiled food, burst pipes, security risk, lost work), you're paying for peace of mind. Fair deal.
If outages are rare (
The UK's flex market is nascent. Grid services might pay £20–50/month by 2027–2028 to homes that offer "demand response". If you believe that upside, V2H infrastructure is a hedge. The payback moves from negative to neutral/positive if £200+/year materialises from grid services. Key: This is speculative. Don't buy on the promise. But if you're already considering resilience, V2G upside makes the £550/year cost more bearable.
If you've already got a home battery (Sunamp, Tesla Powerwall, etc.), V2H is redundant. The battery is cheaper, simpler, more cycles, better integration with solar. Skip V2H; focus on battery + IOG tariff.
If you're serious about V2H, you need:
All grid-connected chargers (V2H or one-way) need a G99 notification to your DNO. It's free, takes 4–8 weeks, and confirms your charger won't blow up the grid. Charger installers handle it. Not a blocker, but expect a waiting period.
✓ Buy an ID.7 lease + IOG tariff? Absolutely. You save £2,977/year vs. a diesel Mercedes. That's transformative for your energy bill and emissions.
✓ Buy an ID.7 + Wallbox + IOG, but only if you live somewhere outages matter? Yes. You're paying £550/year for backup power and resilience. Worth it if your grid is flaky.
✓ Believe in future grid services and want to be ready? Yes, V2H infrastructure is the first step. The payback is speculative today; defensible as a hedge.
✗ Buy a Wallbox expecting to repay it from energy savings? No. The energy arbitrage is negative after roundtrip loss. You're buying resilience, not a financial asset. Accept the £550/year cost as an insurance premium, or skip it.
Run your own numbers—different mileage, different tariff, different car:
→ EV Cost CalculatorInput your annual mileage, tariff rates, and car choice; the calculator shows you Scenario A (standard smart charger) vs. Scenario B (V2H + IOG). It also breaks out the tariff switch value separately, so you can see how much of your saving is due to the charger vs. the tariff.
The electricity market has changed. Five years ago, V2H was speculative; chargers didn't exist. Today, chargers exist. But the energy case is weak.
V2H makes sense for resilience—if your power goes down, your car powers the house. It makes sense as a hedge on future grid services—if flexibility markets pay, you're ready. It does not make sense as an investment in energy arbitrage.
At Rose Cottage, switching from a diesel lease to an ID.7 EV lease, plus Octopus IOG, saves nearly £3,000 a year and cuts emissions by 90%. The Wallbox charger adds £512/year in costs and zero financial benefit.
But it does buy 4–5 days of backup power, rural peace of mind, and a hedge on tomorrow's grid flexibility story.
Price that yourself. For some homes—rural, outage-prone—it's worth it. For others—urban, stable grid—skip it and spend the £5,500 on solar or battery instead.
Published: September 2026
Case study: Rose Cottage, Oxfordshire (IOG tariff, real meter data, 12,000 mi/year)
Vehicles tested: VW ID.7 Tourer
Chargers researched: Wallbox Quasar 2, Zaptec Pro/Go 2, Indra, Enphase
Tariff: Octopus Intelligent Octopus Go (6.90p night, 30.37p day, Sept 2026 rates)